Recent years have seen prevalence of mobile phones provided with the PTT function and of the PTT service which enables one-to-many group communication among the mobile phone users. The PTT function is a voice communication function that enables voice to be transmitted only while the talk button of a mobile phone is pushed. In the PTT service, the only user who is granted the right to speak (hereinafter “Floor”) is permitted to talk.
In addition, during a one-to-many group call enabled by the PTT function, the mobile phone can display a screen including the names and phone numbers of the participants of the group call.